Microwave oven



March 31, 1964 L, p, POLRIES ETAL I 3,127,495

MICROWAVE OVEN Filed Sept. 5, 19,61 2 Shee'bS-Sheeb 2 a INU! l INVENTORS. LOUBS PL POLRBES SYAMUEL. H. ELLOUGH gwdg, jg

United States Patent O 3,127,495 MICROWAVE OVEN Louis P. Polries and Samuel H. Kellough, Minneapolis,

Minn., assignors, by mesne assignments, to Studebaker Corporation, South Bend, Ind., a corporation of Michigan Filed Sept. 5, 1961, Ser. No. 136,088 4 Claims. (Cl. 219-10.55)

This invention relates generally to microwave heating apparatus and more particularly to a novel arrangement for permitting the electrical apparatus which generates the microwave energy used in heating or cooking to be more compactly disposed in a unitary assemblage or cabinet for insertion into the confines of a heating cabinet or oven while the operating temperature of such apparatus is maintained within desirable and proper limits to prevent overheating.

This invention may have as its source the type of microwave heating structure and apparatus disclosed in application Serial No. 49,627, filed August 15, 1960, and its continuation-impart application, Serial No. 97,407, led March 13, 1961. In those applications, a microwave generator for use in cooking was disclosed. Advantageously, such a generator may comprise a magnetron tube having a concentrator centrally disposed in the oven so as to provide improved energy distribution and uniform heating. With this type of arrangement it is possible, for example, to deliver as much as 1000 watts power to the load at 2450 megacycles. At such, or similar power levels, considerable heat is generated. The components of the microwave generating apparatus, therefore, previously were physically distributed over various unrelated parts of the oven in order to be positioned in what was thought to be the most desirable cooling locations. Such distribution, however, resulted in the components being assembled to the oven, and thereby prevented the generating apparatus from being provided as a unitary assembly for simple insertion into the oven cabinet.

To remedy this situation, the inventors have provided a very unusual solution. This solution comprises the disposition of the various components on a single shelf assembly so as to expose the electrical components to a uniquely directed air stream that is in part directed by the components on the shelf. With all the electrical components on the shelf being subjected to the air stream, each is maintained at a proper temperature so that their assembly on the contined shelf space is practical and the shelf with the components in position thereon may be very simply assembled to the oven cabinet by simply inserting the shelf in an appropriate space in the cabinet.

It therefore is a principal object of the present invention to provide an improved cooling arrangement for microwave generating apparatus utilized in heating ovens whereby the components of said apparatus may be mounted in a unitary package for insertion into a microwave oven cabinet.

Among the features of this invention is the utilization of the components themselves for the direction of the air stream and the placement of the blower so that it feeds air directly to the high frequency magnetron tube through a directing passageway to insure the tube being maintained at a proper operating temperature.

The above, together with other objects and features of the present invention, will become apparent on examination of the following specification, claims and drawings wherein:

FIGURE 1 is a general schematic View, partly in crosssection, illustrating the placement of the microwave generating apparatus including a magnetron tube and con- ICC centrator on a single shelf assembly positioned in an oven cabinet.

FIGURE 2 is a perspective View showing the disposition of the various components of the microwave generating apparatus and air control apparatus on the shelf assembly arranged for insertion into an oven cabinet,

FIGURE 3 is a diagrammatic top view illustrating the positions of the various microwave generating and air stream control components together with the air `flow path related to those components.

FIGURE 4 is a generally schematic side elevation of the components shown in FIGURE 3.

In FIGURE l, a microwave cooking oven is identified by the reference character 10. It comprises a heating or cooking chamber 12 defined by a top wall 14, a bottom wall 15 and the depending front and back walls 16. Side walls are also provided although not specically indicated. A door 17 having vents 18 is provided in the front wall 16 to permit one or more trays such as 19 to be placed in the chamber 12. Each tray may carry food indicated at 22 and is supported by shelves or runners 24.

A microwave generating chamber 26 is located beneath the wall 15. It has a front wall 28 in which vents 30 are provided so that air may enter the chamber 26. Microwave generating apparatus indicated generally by the block 32 is located in the chamber 26. The microwave generating apparatus includes a probe and housing 34 therefor associated with and located above a suitable tube, such as a magnetron tube, advantageously positioned centrally with respect to the wall 15. The housing 34 projects through a suitable aperture in the wall 15 into the chamber 12. A concentrator 36 is located in the aperture and the stream of air passing through chamber 26 is circulated past the magnetron tube therebeneath into a duct 38 located at one end of chamber 26. The duct 3S connects directly to a passageway 40 formed between an ofset 42 on the back wall 16 and a wall 44, to circulate the air into the cooking chamber 12.

The microwave generating apparatus 32 is supported on a shelf or wall 46 which is adapted to be inserted in the chamber 26 in any suitable manner, such as sliding the shelf 46 inwardly on rails 48 between the side walls of the oven and then raising the apparatus 32 up into position. The front wall 23 of chamber 26 may be hinged to permit the shelf 46 and generating apparatus 32 to be inserted into chamber 26.

The support shelf 46 has a peripheral flange indicated at `50 against which the cabling (not shown) and conductors extending to the various electrical components may be located, and which further aids in confining the .air iow. 'Iihe support shelf 46 :also has a front or vertical wal-1 portion 52 that terminates adjacent a blower 54 to form 4a passageway 56 through which air from vente 30 may pass. The blower 54 serves to draw air through vents S13-into chamber 26. The wall S2 and iiange 5d may each carry appropriate plugs or sockets such as 53 land passageways for establishing connections ysuch was 53a to external power sources.

`The top and bottom of the passageway 56 `are deiined by the wall 1S and the shelf 46, respectively. The shelf 46 carries a high voltage plate transformer 66 and a baffle plate 60 which serve to deiine the passageway S6 longitudin-ally along one side of chamber Z6. Ain electronic component assembly 62 for the microwave generator is carried by shelf 46 adjacent the one corner or chamber Z6 and in the path of air leaving passageway S6, as shown in FIGURE 3. rPhe lower wall `of duct 3S together with the back wall yof chamber 26 serves to direct the stream `around assembly 62 and across the back lof chamber 26 where it owvs beneath duct 38 and cornes into cooling contact with a filament transformer 64 carried by shelf 46.

The duct 3S is supported at one end by a bracket arrangement 65 carried adjacent the cooling tins S5 enclosed by a housing 51. The magnetron tube is located in cooling ytins S and a cathode box 66 which .is supported on shelf 46. The magnets such as 67 are located adjacent cooling tins 55 inoperative relation to the magnetron tube. The housing 51 has lan opening therein adjacent the cooling tins 55 and this opening is in air flow communication with duct 38. The other end of duct 38 is supported on brackets 68 carried by shelf 46 and is aligned with passageway 40'.

Since the cooling iin housing 51 is located adjacent the center of shelf 46, it aids in maintaining la desired path of air flow circulation about the periphery of charnber 26 so that the air circulates from iilament transformer 64, and past the electronic component assembly 69, into the blower 54 located adjacent the start of passageway 56.

The blower 54 is supported adjacent the front wall 52 on brackets 70. It has a motor 72 and fan blades 7 4 for directing into a scroll duct 76. The scroll duct 76 connects to an appropriate opening in the input side of the cooling iin housing S1. Thus, a coniined, swiftly moving air stream 4is directed past the magnetron tube to cool the latter during its operation. The duct 38 connects to an opening on the output side of cooling n housing 51 so that the air, which is considerably warmed in passing the tube, is now directed through passageway 40 `and through the cooking chamber 12 from which it exits by means of vents y1.8. Advantageously, a take-utf conduit may be provided between the main air stream path and `the cathode box 66 to enable some air to ilow into the cathode box for cooling purposes.

The disposition of the components and the direction given the stream within the ycontines of the 'chamber 26 is an important `feature of this invention, Ias the efliciency with which the air is enabled to perform its cooling lfunction is largely determined Iby the disposition of these components. Thus, it nowv can be appreciated that the microwave generating equipment is disposed in a particularly advantageous fashion on a single unitary assemblage that may be inserted as a unit in an oven cabinet, land that the various components of the microwave generator are disposed in ia continuously moving stream which is directed in a desired cooling path partly 4as a result of the component disposition on a supporting shaft.

It will be noted that the magnetron tube which normally operates :at an elevated temperature is positioned between the exit duct 7 0 of the blower and the entrance port of the duct 38. This position is necessitated by the heating advantages desired, but, at the same time, this location is normally disadvantageous `for cooling. However, with the -fan or blower 54 and the duct 38 serving to move the air stream rapidly past the tube, the tube is maintained iat a satisfactorily operating temperature, while the other components are not subjected to air which has become highly heated in passing the magnetron tube. l

In summary, when the blower 54 is operated, air is drawn in through the ports 30, whereupon it immediately flows through passageway 56 dened in part by the plate transformer S8 land baille 60. Thereafter, the air is guided past the electronic component assembly `62, filament transformer `64 and components 69. The lair is then directed through duct 76 of the blowver 54 and moved rapidly past the magnetron tube and through the duct 38. From the duct 38, it flows through passageway 40 into the heating or cooking chamber 12 and exists through vents 18. Thus, the flow path of the lair stream is directed in a particularly desirable manner, such as the tortuous path described above, tor providing efiicient circulation in a relatively compact microwave generating apparat-us. This desired path yof 4air flow is in part achieved by the planned disposition of the component parts of the microwave generating fi apparatus on a shelf of suiciently compact size so as to permit the entire unitaryassemblage to be preassembled for subsequent insertion into the contines of a heating cabinet or oven.

While there has been `shown and described a particular embodiment -of this invention, it will be `obvious to those skilled in the art that various changes 'and modifications may be made therein without departing from the invention and, therefore, it is intended .in the appended claims to cover 'all such changes and modifications as Ifall within the true spirit and scope of the invention.

What we claim yas new, tand desire to secure by Letters Patent of the United States, is:

l. An arrangement for use in directing the -flow of air past an assemblage of parts comprising a microwave ygenerator adapted to :generate microwave energy in Ka cooking chamber and wherein a microwave generating tube for developing said microwave energy is located adjacent the intersection of two axes of said chamber, the improvement comprising a platform upon which said assemblage is mounted and adapted to for-m one |wall of a microwave generating chamber having another wall formed by the walls of said cooking chamber, one of which has air entrance ports therein, |a high voltage transformer forming part of said assemblage and located adjacent said air entrance ports -for dening a passageway in said chamber, other components of said assemblage disv tributed on said shelf adjacent the periphery of said chamber, a housing for said tube coninlng air tlow from said passageway ,around the periphery of said chamber, and a blower located adjacent said passageway for directing said air against said centrally located magnetron tube, the relative positioning of said wall-s, said transformer and other components, said housing yfor said magnetron tube, and said blower serving to cause said air to ilow in a tortuous path said microwave generating chamber from said air entrance ports to an outlet provided in one of said walls in communication with the cooking chamber.

2. An arrangement lfor use in ldirecting the ow of air past tan `assemblage of parts comprising a microwave generator adapted to generate high frequency energy in a cooking chamber and including a microwave generating ltube located adjacent the intersection of the vertical axes of said chamber, the improvement of means defining la tortuous path ior the ow of air 4within a microwave generating chamber comprising a platform upon which all of said lassemblage of parts are mounted and adapted to kform one Iwall of a generating chamber, a blower, a peripheral flange .on said platform and projecting into said generating chamber, and a housing ttor said tube cooperating with said blower, flange and assemblage for iirst circulating air in a tortuous path past said assemblage to said blower, and means associated with said blower and housing yfor thereafter circulating Iair past said tube.

3. The arrangement claimed in claim 2 in which said assemblage comprise-s a pair of transformers and electronic component lassemblies distributed in sequence adjacent the periphery of said platform.

4. In the arrangement claimed in claim 2, |a duct for directing 4air circulated past said tube into said cooking chamber.

References Cited in the le of this patent UNITED STATES PATENTS 2,632,090 Revercomb et al Mar. 17, 1953 2,831,952 Warner Apr. 22, 1958 2,961,520 Long Nov. 22, 1960 FOREIGN PATENTS 1,249,130 France Nov. 14, 1960 

2. AN ARRANGEMENT FOR USE IN DIRECTING THE FLOW OF AIR PAST AN ASSEMBLAGE OF PARTS COMPRISING A MICROWAVE GENERATOR ADAPTED TO GENERATE HIGH FREQUENCY ENERGY IN A COOKING CHAMBER AND INCLUDING A MICROWAVE GENERATING TUBE LOCATED ADJACENT THE INTERSECTION OF THE VERTICAL AXES OF SAID CHAMBER, THE IMPROVEMENT OF MEANS DEFINING A TORTUOUS PATH FOR THE FLOW OF AIR WITHIN A MICROWAVE GENERATING CHAMBER COMPRISING A PLATFORM UPON WHICH ALL OF SAID ASSEMBLAGE OF PARTS ARE MOUNTED AND ADAPTED TO FORM 